Superheating of interstage steam



June 24, 1930. 0. H. HARTMANN 1,768,058

SUPERHEATING OF INTERSTAGE STEAM Filed July 11, 1928 2 Sheets-Sheet 1Fig.7.

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June 24, 1930. I o, HARTMANN 1,768,058

SUPERHEATING OF INTERSTAGE STEAM Filed July 11, 1928 2 SheetsSheet. 2

Patented June 24', 1930 omen STATES OTTO H. HARTMANN, OFCASSEL-WILHELMSHOHE, GERMANY, ASSIGNOR TO SCHMIDTSCHEHEISSDAMPF-GESELLSCHAFT MIT BESCHRAINKTER HAF'IUNG, OF

CASSEL-WILHELMSHOHE} GERMANY, CORPORATION OF GERMANY surnnunermo or mrnnsraen STEAM Application filed July 11, 1928, Serial No. 291,802, and.in Germany July 29, 1927.

My invention relates to an arrangement for the superheating ofinterstage steam, more particularly in marine steam plants, by means ofa heat carrier in the form of steam in marine boilers with a return forthe hot gases. The superheatimg of the interstage steam of multi-stagesteam engines reversing chamber in the form of a radiation boiler (seeFigures 1 and 2 of the U. S. Patent No. 1,618.230. filed Dec. 15. 1920,and

granted to Wilhelm Schmidt). The advantage of such an arrangement liesmainly iii this that for the superheating of interstage steam byhigh-pressure condensing tre'sh steam it is suflicient to producecomparatively small quantities of heating steam and that v consequentlythe heating surface to be built in can be made comparatively small. Thisheating surface absorbs from the heating gases only-so much heat that .asuflicient quantity of heat still remains available for therequired-high superheating of the working steam produced in the mainboiler, which" superheating is ,effected in the heating tubes ofthemarine boiler which are provided with comparatively superheating tubes.The

7 small reduction in the super-heating of the working steam caused bythe building in of the heating elements of the high-pressure auxiliaryboiler is morethan compensated by the advantage gained by the highsuperheating of the interstage steam in the low pressure stage.

existing marine boiler installations in order to'improve theiroutput ina known manner by constructing into the existing engine a low pressurestage, more particularly an exhaust-steam turbine, and superheating theinterstage steam. The obvious solution, of

building the heating coils of the high-pressure auxiliary boiler in thesmoke box attached to the chimney, in which there is suflicient spacefor accommodating a comparatively large heating surface, does not comeinto question since the heating gases before arriving at this point havesupplied too much heat to the'heating surface of the main boiler and tothe superheating elements builtin the a heating tubes.

According to my present invention the problem is satisfactorily solvedby the heated part of the auxiliary steam generator lying in thereversing chamber being construct ed, in a manner well known inconnection with superheaters, viz., as heating coils with U-shapedreturn bends which are inserted from the outside into the reversingchamber. In single ended Scotch boilers, the U-shaped bends of theheating coils are inserted through flanged sockets which are providedafter removal of thestaybolts between the end of the boiler and the wallof the reversing cha'.nber.. In the case of the double-ended Scotchboilers, according to one suitable form of construction, the heatingcoils of the auxiliary boilenwhich generates the heating steam for thesuperheating of the interstage steam are inserted with their reversingends into the reversing chamber, which lies in the centre, through aportion of the heatingtubes of the working boiler, the remaining portionthereof being provided with the superheating coils of the'workin'gboiler.

The accompanying drawings illustrate diagrammatically and by way ofexample the two forms of construction above referred to, Figures 1 and2.be1ng a sect1onal elevation and end view respectively of the firstform of construction and Figure 3 a sectional elevation of the secondform of construction.

Referring to Figures 1 and 2 Whichillustrate an existing single-endedScotch boiler, the staybolts between the end 1' of the boiler stayboltswhilst they allow at .the same time the tubes of the heating coils 4 ofthe auxil-' iary boiler to be passed through. The auxiliary boiler isprovided with an upper drum 5and a lower Water collecting drum 6 and ispartly filled with the heat carrier, for instance distilled water. Thewater circulates in a closed cycle through the heating coils of theinterstage superheater 7 provided on the engine, in the direction of the,arrows, thereby changing its physical state, the condensate beingreturned through the pipe 8 into the drum 5. In normal operation thewhole of the heating steam passes through the pipes 9 and'lO and over anautomatically acting stop valve 11 into and through the interstagesuperheater 7. However, when the pressure and temperature in theauxiliary boiler exceeds the normal values, the valve 11 opensautomatically, so that the eX- cess of heating steam passes in a knownmanner througha heating coil 12, thereby giving up its excess heat tothe water of the working boiler 1. The superheater 13 for the workingsteam generated in the boiler 1 is built in aknown manner in the heatingtubes 14; of the working boiler. heating gases have passed through theflue tube 15, they give up a portion of the heat,-

which they 'still'contain in large quantity, to the heating coils 4 ofthe auxiliary boiler which project into the reversing chamber 2, so thatthe heating surface of the auxiliary boiler required for the interstagesuperheating "iscomparatively small This permits the heating surfacerequired for the auxiliary boiler to be subsequently incor orated in asimple manner in an existing single-ended marine boiler. The places ofinsertion of the heating coils are made air-tight in a suitable manner,for instance, by 'means of divided plates with asbestos insertions.

In the case of a double-ended Scotch boiler, such/ as illustrated inFigure 3, the carrying out of the invention is even more simple in sofar as a portion of the heating tubes 14 of" the boiler can be,used for,the passage of the heating coils of the auxiliary boiler, in order topermit the return bends of the heating coils to project into thereversing chamher 2. Although-i n this form of construction the heatingcoilsare lon er and ass through some of the heating tub which otherwisethe superheating tubes for I the superheating of the working steam wouldbe accommodated, this is only an apparent disadvantage, when it is bornein mind that by incorporatingan exhaust steam turbine and providing for.the superheating of interstage steam by means of high-pressure freshsteam, the steam consumption is reduced to suchan extent that thereduced superheating After thees of t 'e boiler, in

nveaoae surface more than suffices for the smaller amount of Workingsteam to be generated per hour. Otherwise the construction is the sameas that shown in Figure 1, for which reason the same reference lettershave been used in both drawihgs and the arrangement need not be furtherdescribed. I I

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed. I declare thatwhat I claim is:

1. An arrangement for the superheating of interstage steam in marinesteam boilers provided with a reversing chamber for the hot gases andhaving live steam superheater elements arranged in its heating tubes, bymeans of a heat carrier in the form of steam which circulates in aclosed cycle through its steam generator and the heating coils of theinterstage superheater and which is produced by an auxiliary steamboiler having its heated part lying in the reversing chamber, the saidheated part projected into the reversing chamber from the outsidethereof.

.2. An arrangement as claimed in claim 1 used in connection withdouble-ended Scotch boilers, in which the heated part comprisescoilshaving U-shaped return bends which are inserted into the reversingchamber ly ing in the centre of the working boiler through a portion ofthe heating tubes of the working boiler, the other portion of whichaccommodates the superheating coils of a live steam superheater for theworking steam.

3. An arrangement for the superheating of" interstage steam in marineboilers provided with a reversing chamber for the hot gases andhavinglive steam superheater elements arranged in its heating tubes, bymeans of a heat carrier in the form of steam which circulates in aclosed cycle through its steam generator and the heating coils of anintersaid heated part being constructed in theform of heating coilshaving U-shaped return bends, each of the U-shaped return bends beingintroduced into the reversing chamber through an individual opening inthe wall thereof.

Intestimony whereof I have aflixed m signature.

OTTO H. HARTMANN.

